CS-7 Shellside Condensation of Ethylene Glycol/Water Mixtures on Plain and Finned Tubes
Condensation data for mixtures of ethylene glycol and water at low pressure on the shellside of a baffled shell and tube exchanger are compared with predictions of HTRI Computer Program CST-2, Mod. 0.11-1.08.
It was found that for the plain tubes, the HTRI Resistance Proration Method was optimistic in gravity controlled flow. The HTRI Composition Profile Method, which does a better job of accounting for mass transfer resistance, was conservative. However, it could be adjusted for good prediction by increasing the mass transfer coefficient as a function of the HTRI flow regime parameter.
For the finned tubes, prediction was much more difficult, presumably because of mixture surface tension and viscosity effects. In general, performance was much better for the mixtures with high water concentration than with high glycol concentration. This was an unexpected result, and possible reasons are proposed. Improved prediction for the finned tubes will require further analysis. Parametric effects are discussed and suggestions for further development are made.